Electrical connectors for interconnecting pluralities of circuit members such as mentioned above in computers and similar equipment are known in the art, with representative examples shown in U.S. Pat. Nos. 4,664,458 (Worth), 4,863,387 (Snaper et al), 5,127,838 (Zaderej), 5,160,268 (Hakamian) and 5,174,763 (Wilson). Typically, such connectors are designed for being positioned between the two circuit members to be coupled with designated contacting elements or the like of the connector projecting or extending from the connector to effect contact with respective conductive members (e.g., flat copper pads) located, usually, on an external surface of the circuit member. Contact is completed in most situations through use of some compression or clamping means that moves one or both of the circuit members toward the other to compress the connector therebetween.
While many such connectors are known to exist, very rarely has consideration been given in the design of such with respect to impedance matching between the connector and one or more of the circuit members. Such is particularly the case with respect to connectors of the high density variety (e.g., those which utilize a plurality of contacts positioned adjacent one another at spacings as close as about 0.050 inch or even less). Impedance matching, as is known, is the process of making equal the impedance when looking both ways from a junction location in two parts of a circuit. In the particular ease of the aforementioned connector structure, this capability serves at least two important functions: (1) it provides a condition of maximum power transfer from one circuit to another for resistive impedances; and (2) it also serves to prevent reflection of voltage and current waves.
In typical computer systems, printed circuit boards and other circuit members are often associated with an established impedance, usually at a level of, say, 50, 70 or 93 ohms. In order to assure the above highly desirable features, therefore, it is important to provide a connector with an associated impedance at a value similar to (matching) these. U.S. Pat. No. 5,174,763 represents one example of a connector which couples two circuit members in a "high density" arrangement with minimum crosstalk (between contacts), selected impedances and minimum inductances. In this patent, a plurality of pairs of projecting probe-type contacts are utilized, each pair associated with some form of spring means which is required to assure external projection. The contacts each include tipped end portions which physically engage the respective conductor pads on the circuit members after passing through provided holes in the outer part of a "frame" designed to accommodate the contacts therein. "Bushing" portions of the frame, located between the contact and an also required ground plating, are apparently intended to provide some form of control of characteristic impedance.
As will be defined hereinbelow, the present invention comprises an electrical connector for interconnecting first and second circuit members wherein a selected level of impedance is substantially assured to thereby match that of one or both of the circuit members and thereby assure the above and other desired features. The invention, while thereby greatly facilitating design of the overall structure using the connector, is uniquely able to provide such a capability with a relatively uncomplicated design, not requiring the several individual elements demanded in U.S. Pat. No. 5,174,763. Significantly, the invention is able to do so and still attain sound, effective coupling at the desired locations. Equally significant, the invention is also able to do so with several contact members closely positioned together in a highly dense arrangement, while also substantially preventing "crosstalk" between adjacent contacts, an undesirable characteristic, particularly in complex electrical structures such as computers.
It is believed that such a connector represents a significant advancement in the art.